Luminaires capable of adjusting the shape of the emitted light beam find their way in many applications. The beam shaping feature is highly interesting, both in static as well as in dynamic applications. Adjustable beam shapes in static application are normally implemented through a number of preset modes, for instance ‘spotlight’, ‘floodlight’, or ‘ambient light’. In applications using dynamic beam control, the beam shape can normally be adjusted over a continuous range.
In conventional luminaires, the emitted light beam is created through the use of a light source and an optical system. The optical system usually is a reflector system but may also be a refractive system, a diffractive system or a diffusive system. Adjusting the relative position of the light source and the optical system classically controls the beam shape. Taking a torch as an example, repositioning the light bulb relative to the parabolic reflector (or the lens relative to the light bulb) controls the shape—narrowly focused vs. wide flooding—of the light beam. Applying switchable refractive elements—e.g. liquid crystal lenses and electro wetting lenses—or switchable diffusers constitute alternative well known technologies to adjust the beam shape emitted by a luminaire.
A drawback of the prior art technology to adjust the beam shape of the light emitted by a luminaire is the use of adjustable optical systems, either through mechanical movement or electrical control. While moveable systems are prone to wear and tear, electrically controllable systems are usually highly complex and expensive. Furthermore, the bandwidth of the mechanical moveable and electrically controllable optical systems usually is limited to the frequencies with which the optical system can be adjusted. Typically the bandwidth is 10-100 Hz for mechanically moveable systems, up to 10 kHz for rotating systems, 100 kHz-1 MHZ for micromechanical systems (MEMS), and 50-1000 Hz for electrically controllable systems.